The difference of pressure between the inside and outside of a liquid drop is ________?

Maximum principal stress theory is applicable for________?

Air fuel ratio for idling speed of a petrol engine is approximately________?

Which of the following is not the unit of pressure?

The thermal diffusivities for solids are generally________?

Efficiency of a Carnot engine is given as 80%. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle________?